Jack chases a Weevil into an alleyway. He's equipped with hand-clamps and anti-Weevil spray. The alien attacks him, ripping open his chest, and Jack complains that's what happens when he gives the team the night off.
Rhys has taken Gwen out but she's distracted and he calls her on it. He wonders if he's to blame and she apologizes. However, Gwen runs up and asks her to accompany him. Rhys yells at Gwen to stay with him and she tells him never to speak to him that way. As she goes, Rhys starts to threaten her if she doesn't return but she ignores him. As they go Jack, tells her not to let go of her life. They track the Weevil to a car park and see black-clad figures emerge from a van, abduct the Weevil, and drive away.
Back at the Hub, Ianto reports a surge of unusual injuries at the A&E unit. All of them involve Weevil-related injuries. Jack reports that their anti-Weevil spray isn't working. The license plate on the van is a fake. While Tosh tries to trace the van per CCTV, Jack tries to reach Owen by phone ad Gwen leaves a message on the phone apologizing to Rhys. He listens without answering and then deletes the message.
Owen is at a bar drinking and ignoring his buzzing cell phone. The female bartender tries to give him some advice and her boyfriend Tommy objects. Owen tries to interfere and easily subdues Tommy when he starts a fight.
Back at the Hub, Tosh mentions Owen's recent thing with Diane and how he's been more erratic since then. Gwen asks for more details and Tosh tells her that Gwen and Diane were involved. She's surprised to hear it was serious. In the cells, the captive Weevil starts moaning and Jack realizes that it's weeping. The Weevils have a low-level telepathy and they believe it's feeling the pain of another of its kind.
Tosh tracks the van to a warehouse before the abductors cut out the CCTV. They go to the warehouse and Jack and Tosh move in to search. They find a human male corpse, his body covered in Weevil wounds. The man's cell phone rings and Jack answers. The man at the other end tells him to leave off, but Jack warns him that they'll track him down and recover the Weevil. The caller cuts off and Jack calls Ianto have him run a trace.
Jack finally gets hold of Owen on his cell phone and orders him back to the Hub. He performs an autopsy while Gwen confirms the dead man was a salesman. Owen confirms the dead man was beaten before the Weevil killed him, and Weevils usually kill immediately. They wonder why someone would beat a man before using a Weevil to kill him. Ianto's trace turns up a dead end. Jack figures someone is using the Weevils to perform untraceable murders. When Gwen points out someone should break the news to the widow, everyone looks to her.
Owen drives her to the widow's house and Gwen breaks the news. Once she's done, Gwen admits that she's upset and turns to Owen for sympathy. He all but ignores her and he gets out as she drives away. Owen walks back to the Hub where Tosh has figured that the abductors own real estate such as the warehouse. Owen is the only one the abductors couldn't have seen yet via CCTV.
Owen goes undercover as a jellied eel supplier and meets with real estate agent Mark Lynch. He claims to be looking for premises out by the dock and has no family. While Lynch runs the paperwork, Owen establishes a link to his computer. Lynch gives him papers on various properties and Owen points out they're all garbage. Owen asks about the warehouse where the man was found and Lynch claims it's already sold. Tosh confirms he's lying and Lynch invites him out for a drink to discuss the matter. Owen agrees and leaves. Lynch runs a computer search on Owen and confirms he's legitimate, thanks to Tosh's setting up information for him to find. Ianto has found another set of suspicious injuries at a hospital and Jack takes Ianto with him. When Gwen volunteers, Jack tells her to go home and keep her life from drifting.
Gwen returns home to find Rhys, who is leaving for a friend's single stag party. He refuses to tell her when he'll be back and ignores her when she says she'll be in.
Jack and Ianto talk to the victim, who nearly had his heart tore from his rib cage. Jack describes a Weevil but the man insists he was mugged by three men. They warn him that the creature will attack again and it'll be on his conscience. The victim insists that he can't tell them the truth or "everyone" will kill him.
Jack only has one option left. They take out their Weevil, release it with a hidden tracker, and track it to the people who take it. Tosh and Ianto think it's too dangerous but Jack drops it off at the same spot where the last Weevil as abducted. They follow it in the SUV but it goes down a pedestrian access and Jack and Tosh follow on foot.
Owen meets Lynch at the same bar he was at earlier. Tommy and his two friends come over and attack Owen. Lynch comes to his aid and the two of them easily take care of the three attackers. Owen beats Tommy repeatedly and Lynch appears impressed.
Jack and Tosh move in as the abductors capture the Weevil. They watch as the alien is taken away. Once the van leaves, Tosh notes that they wouldn't put a human through the same thing. Ianto arrives to pick them up.
Lynch takes Owen back to his apartment. Lynch asks how Owen releases his anger, noting he's already got people coming after him. He questions what Owen gets out of life and says there's more if he just knows where to look. He says that something out in the darkness is coming.
Gwen is waiting with two drinks when Rhys comes home early from the party. He sits down and they drink She finally tells him that she's been having sex with someone else from work. Rhys insists she wouldn't do that but Gwen admits she did and needs him to forgive her. She also reveals that she drugged him with Retcon to make him lose his memory. She begs him to forgive her before he passes out, but he doesn't say anything.
Owen goes up to the bathroom and finds a locked room. He picks the lock and finds a captive Weevil. Mark comes in and asks what Owen thinks of it. He explains that he and some others found it and have no idea what it is. Lynch speculates that the Weevil is what they'll become when all they have is rage. The real estate agent hammers it like a punching bag and invites Owen to do the same. When Owen balks, Lynch asks if he's connected to Jack and Tosh and admits he wasn't fooled by the web site. He wants to know why they take Hodges' body and didn't go to the cops. Owen shows him his gun but Lynch says he'll need to refuse to hide behind it to learn what they're up to. Once Owen discards it, Lynch says that Hodges was one of them and that they didn't use the Weevils for murders. He offers to take Owen with him to show what they are doing.
Gwen returns to the Hub with pizza but no one's there.
Jack, Tosh, and Ianto track the Weevil but discover that the abductors have discovered the tracer and left it on a fence.
Lynch takes Owen to watch as men assemble at a hidden club. They finally go inside.
As Gwen waits, she eats some pizza and breaks down crying. As she checks her calls, she notices Hodges' body lying on the autopsy table. She checks Hodges' cell phone and discovers an incoming text message stored on it with an address. She calls Jack and tells him it's a Lynch property that he knows is empty. They head for the Hub to pick up Gwen.
Lynch takes Owen into the building where men are fighting as a warm-up. The real estate agent talks about how he and the others are the dispossessed and they've reduced themselves to the basics. He takes Owen to a large room where a man is fighting a Weevil in an electrified match cage. The man finally gives up and gets out before the Weevil kills him. Lynch explains that the group members pay a thousand pounds to enter the cage, and the one who stays in the longest gets all the money for the night. He admits that Hodges died, but only because he surrendered and didn't fight back or try to get out. Owen insists it has to stop before more people die. Lynch wonders how long Owen is going to stop hiding, and then draws a gun and orders him into the cage. Owen tells him to lower the gun and then he'll get into the game. Lynch considers it for a minute and then lowers the gun.
Owen enters the cage and Lynch locks him in. Owen looks down the Weevil and then smiles and dares it to attack. Jack and the others break in and the Weevil leaps onto him. Jack shoots the Weevil and Gwen goes to Owen's aid. He tells her to leave him alone but they pull him out. Jack accuses Lynch of doing it to Owen, but Lynch says that Owen did it to himself. Jack tells the crowd to leave the creatures alone and go back to their lives. Lynch enters the cage and stares the Weevil down for a moment. Jack turns away as the Weevil rips Lynch apart.
Later, Jack goes to see Owen in the hospital. Owen insists that he didn't want saving and admits that for a few seconds in the cage, he felt totally at peace. He wonders if Jack always knows best. Jack tells him to be back at work tomorrow and leaves.
The next day, Owen goes to the cells to confront the Weevil alone. He looks at it and then snarls, and the Weevil backs away as Owen smiles in satisfaction.